What are food allergies and food intolerance?
Food allergy is an abnormal immune response caused by contact with specific foods, which has adverse effects on health. Food allergy may be IgE-mediated or non-IgE-mediated. When the immune system produces IgE antibody to food, IgE-mediated food allergic reaction will occur; These antibodies bind to mast cells and basophils and stimulate the release of pro-inflammatory cytokines, thus inducing acute and sometimes life-threatening allergic reactions. Non-IgE-mediated food allergies involve other components of the immune system, which may take several days to show.
On the other hand, food intolerance is a non-immune response to food. These reactions are usually related to enzyme deficiency, malabsorption or sensitivity to certain food ingredients. They can cause various gastrointestinal and inflammatory symptoms. Food allergy and food intolerance will obviously reduce the quality of life, damage health, reduce the pleasure of eating, and cause high vigilance against allergens lurking in food.
The incidence of food allergy and food intolerance is rising.
Nowadays, food allergies and food intolerance have become commonplace, and many food packages will be marked with potential allergens. However, before 2000, the incidence of food allergy did not seem to be high, but in the past 10-20 years, the incidence of these diseases rose sharply. It is found that in industrialized countries including the United States, Britain, Australia and China, more than 20% of the population suffers from food allergy or food intolerance.
Although the number of people with food allergy and food intolerance has risen sharply, there are few treatment options available. Traditional medicine advises patients to strictly avoid foods that cause allergies and prepare adrenaline to prevent accidental contact. However, none of these strategies can solve the potential causes of food allergy and food intolerance, and new treatment methods are urgently needed.
A series of new studies show that the changes of intestinal flora in normal people play an important role in the occurrence of food allergy and food intolerance. Regulating intestinal flora can reduce food allergy and food intolerance, and restore tolerance to triggered foods.
hygiene hypothesis
The human body carries trillions of bacteria, the number of which far exceeds the number of human cells. Humans have evolved with these bacteria, and their existence in our bodies is very important for our health. This concept has been clarified in the "health hypothesis". The health hypothesis holds that the lack of contact with microorganisms in childhood will change the intestinal flora and inhibit the normal development of the immune system, thus increasing the sensitivity to allergic diseases. Some lifestyle factors that reduce early microbial contact will deprive the immune system of the stimulation it needs to prevent allergic diseases. Factors to reduce microbial exposure include, but are not limited to:
In industrialized countries, infants and children often receive multiple courses of antibiotic treatment in early life, which has a great impact on the immune system and may increase their risk of food allergy. The use of antibiotics by pregnant women before and during pregnancy can also lead to imbalance of intestinal flora and increase the risk of food allergy in children. In addition, the widespread use of antibiotics in agricultural production also leads to antibiotic residues in meat, dairy products and eggs, and long-term intake of such foods containing antibiotic residues may also lead to intestinal flora imbalance.
Contact with some synthetic chemicals will destroy human intestinal flora. For example, triclosan is a synthetic antibacterial substance, which is added to many daily necessities such as toothpaste, antibacterial soap and hand sanitizer. P-hydroxybenzoate is a common preservative. It has been proved that they are related to food allergen sensitization.
Western diet is characterized by high saturated fat, high refined carbohydrates and lack of important nutrients, which is related to increasing the risk of food allergy and food intolerance. The relationship between diet and the risk of allergic diseases seems to begin early in life. Studies have found that babies who eat more vegetables, fruits and homemade foods in the first year of life are less likely to suffer from allergic diseases than those who eat less of these foods.
Babies born by caesarean section cannot get lactobacillus and bifidobacteria from their mothers' birth canal, which may increase the risk of allergic diseases in children.
Breastfeeding plays an important role in the establishment of intestinal flora and immune development of infants, and formula milk powder feeding will change this process, which is related to the increased risk of allergic diseases.
In industrialized society, most people spend a considerable part of their lives indoors, and the time for outdoor activities is greatly reduced. Studies have shown that our separation from the natural environment has significantly reduced the bacterial diversity of human intestinal flora and is related to the increase of allergic diseases.
Changes of intestinal flora and food allergy and food intolerance
There are significant differences in intestinal flora between food allergic and non-allergic people, so the changes of normal intestinal flora may play a role in the pathogenesis of food allergy and food intolerance. The normal intestinal flora of human body consists of many kinds of bacteria, including Bacteroides, Enterobacteriaceae, Bifidobacterium and Lactobacillus. These bacteria interact with the intestinal mucosal immune system to promote immune tolerance to food. Some unhealthy lifestyle factors that reduce the number of beneficial bacteria in the intestine will destroy immune tolerance and lead to food allergy or intolerance.
The changes of some types of intestinal bacteria are related to the occurrence of food allergy. Most studies on this phenomenon are carried out on infants and children. In children, the decrease of Lactobacillus and the increase of Staphylococcus aureus are related to egg and milk allergy. In the first two months after birth, children with low levels of Lactobacillus rhamnosus, Lactobacillus casei, lactobacillus paracasei and Bifidobacterium adolescentis are at higher risk of allergic reaction to milk, egg white and inhaled allergens. The decrease of bacteroides, Proteus and actinomycetes is also related to infant food allergy.
In addition to increasing the risk of food allergy, the lack of intestinal bacterial diversity may also lead to non-immune food intolerance, such as gluten intolerance, FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) intolerance and histamine intolerance. Some kinds of bacteria contribute to the decomposition of gluten protein, and the lack of these bacteria may lead to gluten intolerance. Overgrowth of intestinal bacteria is a common cause of FODMAP intolerance. Histamine intolerance may occur when histamine-producing bacteria or bacteria that produce enzymes that interfere with histamine metabolism overgrow.
Application of Probiotics in Treating Food Allergy and Food Intolerance
The therapeutic application of probiotics may become a new breakthrough in the prevention and treatment of food allergy and food intolerance. It has been found that prenatal supplementation with Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus and Lactobacillus rhamnosus can prevent food allergy in infants with familial food allergy tendency. Supplementing pregnant women and their babies with Lactobacillus salivarius, lactobacillus paracasei, Bifidobacterium animalis and Bifidobacterium bifidum can significantly reduce the incidence of infants' atopic allergy to common food allergens.
Postpartum probiotic supplementation can also reduce atopic allergies and may reverse food allergies. Supplementation of Lactobacillus rhamnosus to infants with milk allergy can promote tolerance to milk protein, thus reversing sensitization. For older children allergic to milk, Lactobacillus rhamnosus can enhance the production of anti-inflammatory cytokines IL- 10, thus alleviating allergic symptoms. A meta-analysis found that early supplementation of Lactobacillus and Bifidobacterium can reduce the risk of atopic allergy in children.
It is worth noting that most studies to evaluate the efficacy of probiotics in the treatment of food allergies are conducted in prenatal care, infants and children. The composition of intestinal flora in early life is different from that of adults, so the probiotic intervention discussed here may be more conducive to preventing and reversing food allergies in children, and more research is needed to determine whether probiotics can alleviate food allergies in adults.
In addition to preventing and reversing children's food allergies, probiotics may also be beneficial to treat food intolerance. Supplementation of compound probiotics including Lactobacillus, Bacillus coagulans and Saccharomyces boulardii can significantly alleviate the symptoms of patients who are not sensitive to celiac gluten. Probiotics, such as Bacillus coagulans and Lactobacillus acidophilus, can reduce the overgrowth of intestinal bacteria, which is a problem related to FODMAP intolerance. Finally, the overgrowth of histamine-producing bacteria in the intestine may lead to histamine intolerance. Therefore, for people with histamine intolerance, avoiding histamine-producing probiotic strains and supplementing degradable histamine strains may help to alleviate or alleviate histamine intolerance. Histamine-producing probiotic strains include Lactobacillus Roy, Lactobacillus casei and Lactobacillus bulgaricus. The strains that can degrade histamine include Lactobacillus rhamnosus, Lactobacillus plantarum and Bifidobacterium. Although probiotic treatment of food allergy seems to be mainly beneficial to infants and children, the benefits of probiotic treatment of food intolerance can also be extended to adults.
Action mechanism of probiotics
Probiotics can improve food allergy and food intolerance through various mechanisms:
The role of prebiotics
Prebiotics can enhance the role of probiotics by promoting the proliferation of probiotics in the intestine. Some studies have found the connection between supplementing prebiotic oligosaccharides and reducing the incidence of allergic diseases.
In addition, pure natural food is rich in nutrition and can provide additional protection against food allergies and food intolerance. The intake of Omega-3 fatty acids, vitamins C, E and A, β-carotene and zinc can reduce the incidence of food allergy.
On the contrary, if the diet contains a lot of refined carbohydrates, artificial sweeteners, omega-6 fatty acids and food additives, it may increase the risk of food allergy and intolerance.
Some people think that eating genetically modified foods may also increase the risk of food allergy and intolerance, which is due to the potential allergenicity of technically modified proteins in these foods, but there is still no conclusive evidence.
Suggestion:
Food allergy and food intolerance have become very common in modern society. At present, avoiding certain foods is the most effective way. Therefore, they should be more careful when eating, and also lose a lot of fun to enjoy food, which obviously reduces the quality of life. In view of the relationship between intestinal flora and food allergy, for people with food allergy or people with high risk of food allergy, we suggest:
The pictures are all from the Internet.